Portable battery powered electrical devices such as radios, telephones and flashlights are well known. It is also well known to electrically power such devices using generators which convert manually input mechanical energy into the electrical energy used by the device. Speck, U.S. Pat. No. 3,099,402 shows that a battery can be included as an alternate source of electrical power and that the generator current can serve to recharge the battery as well as power the bulb of a flashlight.
Manual input may be either direct as in the case of McNath, U.S. Pat. No. 2,424,700, or indirect through storage in a spring as shown in Speck, allowing extended operation with only periodic winding of the spring. Spring based storage suffers primarily from higher manufacturing costs, limited storage capacity, wear and eventual breakdown of the spring over repeated operation cycles, the potential for overwinding, and a bulkier housing capable of containing the spring in both wound and unwound states.
It has been shown by Jimena, U.S. Pat. No. 4,315,301 that instead of a spring, a high inertia flywheel may be used to store manually input mechanical energy. The spinning flywheel also provides a gyroscopic effect which helps to stabilize the flashlight orientation during manual input.
However, flywheel based storage suffers from both bulkiness and weight. The kinetic energy stored in a rotating body is increased by increasing its mass or by locating its mass at a greater distance from the body's axis of rotation. Therefore, for greater energy storage, the flywheel should be large or massive or both. However, neither of these two design criteria are desirable in a portable devices. Therefore, most designs strike a compromise between portability and energy storage. In addition, flywheels are costly in both material and fabrication since both dense and durable materials such as metals like iron or steel are preferred.
Various manual input means such as disclosed in Speck and Jimena have mechanisms which may subject the user's hands to pinching between the levers and flashlight body and/or the gearing.
With respect to the battery recharging ability of manually activated generators, it is desirable to recharge as quickly as possible. This is furthered by a well regulated, efficiently supplied high voltage to the battery. Current manually operated generators suffer from relatively low output over a given time period.
It is therefore desirable to have a portable handheld electric device which is at least partially manually powered and which reduces the above identified problems.